function fnTrapKD(btn, event)
{
 if (document.all)
 {
  if (event.keyCode == 13){
    FirePostBack(btn, event);
  }
 }
 else if (document.getElementById){
  if (event.which == 13){
   FirePostBack(btn, event);
  }
 }
 else if(document.layers){
  if(event.which == 13){
   FirePostBack(btn, event);
  }
 }
}

function FirePostBack(btn, event){
    // if you get an error here check that the code for 
    // SetDefaultButton in the ac/utils/utils.vb file
    // contains ' around the name for the button client id.
    event.returnValue=false;
    event.cancel = true;
    var postbackid = btn;
    while (postbackid.indexOf('_') > -1)
    {
        postbackid = postbackid.replace('_', '$');
    }  
    __doPostBack(postbackid,'');
}